Though unearthed nearly 15 years ago, scientists were unsure of the fossil's identity. Paleontologists knew the specimen belonged to the mosasaur family, a group of large marine reptiles, but couldn't determine which.

When researchers compared the miniature fossil to the bones of two related species, T. nepaeolicus and T. proriger, they were able to confirm the lizard's identity. The ancient bones represent an infant Tylosaurus mosasaur.

Scientists were thrown off by the lack of the species' trademark anatomical feature.

"Having looked at the specimen in 2004 for the first time myself, it too took me nearly 10 years to think out of that box and realize what it really was -- a baby Tylosaurus yet to develop such a snout," Takuya Konishi, professor at the University of Cincinnati, said in a news release.

"Yet again, we were challenged to fill our knowledge gap by testing our preconceived notion, which in this case was that Tylosaurus must have a pointy snout, a so-called 'common knowledge,'" said Konishi.

Because individual development patterns and the evolution of a species are often correlated, scientists think the oldest Tylosaurus specimens likely featured shorter snouts.

The largest Tylosaurus specimens grew to 42 feet in length, with their large heads accounting for one-sixth of their body length.